This invention relates to an apparatus and method for non-destructively inspecting various bodies or objects using a moving transducer array, specifically in combination with a liquid crystal ultrasonic detector cell.
Ultrasonic examination of various bodies or objects is well known in both the medical and industrial fields. Typically an ultrasonic transducer is provided which emits an insonifying ultrasonic beam which is directed to an object. The ultrasonic beam passes through the object, is received by a detector and an image is generated. Liquid crystal detector cells which display an image are disclosed in various U.S. patents. See, for example, U.S. Pat. Nos. 4,379,408; 4,338,821; 3,579,054; 3,707,323; 3,831,434; and 3,879,989.
In these systems, the ultrasonic transducer may be a single transducer which is held in position or a plurality of transducers held in position which are sequentially excited so as to produce an image.
However, in order to inspect a larger object, such as an aircraft wing or a fuselage section, it is necessary to provide a large and uniform ultrasonic beam. The prior single fixed position transducer or fixed position array which is sequentially excited do not provide a large uniform beam and have not produced desirable results for inspecting such objects or sections.
Rotatable wheels have been suggested for inspecting larger objects in which transducers are aligned along the radii of the wheel and are carried on the circumference or the periphery of the wheel so as to contact the object as the wheel is rolled. See for example, U.S. Pat. Nos. 3,423,994; 3,541,840; and 3,771,354. These devices are believed to be too cumbersome, not sufficiently flexible in their use and do not appear to be adaptable for use with liquid crystal detectors.
A rotating transducer array is shown in U.S. Pat. No. 3,280,621 in which the sending transducers are focused at a point on the axis of rotation and the receiving transducer is mounted on the axis of rotation for receiving reflected signals. In view of the focused nature of the beam and the fact that the maximum insonified area is limited to the profile of the array and can only be increased to that limit by moving the array toward the object, this device is not believed to be suitable for use in inspecting large objects. Furthermore, this device is not intended for use with a liquid crystal display cell.
Single transducers have been used in the pulseecho mode to scan objects and produce what are known as "C-scans". However, such systems are extremely slow to produce an image and have not been employed with the liquid crystal detector cell.
It is therefore the primary object of this invention to provide an ultrasonic signal source which is uniform, which can insonify large objects, and which can be used with liquid crystal detector cells.
This and other objects of this invention will become apparent from the following description and appended claims.